conventionally, there is proposed an internal combustion engine having a double tank type oil pan. For example, Patent Reference 1 discloses a system including an oil communication path enabling bidirectional oil flow between an inner tank (a first tank) and an outer tank (a second tank), and a valve mechanism provided on the oil communication path. Specifically, Patent Reference 1 discloses that the communication between the inner tank and the outer tank is cut off by the operation of the valve mechanism in a case where the temperature of the oil in the inner tank is lower than a predetermined valve-opening temperature.
Further, Patent Reference 2 discloses a technique relevant to the present invention.